What is the extent to which a research tool measures what it is supposed to measure?

The extent to which a research tool measures what it is supposed to measure is referred to as validity. Validity is essential in research as it ensures that the results obtained truly reflect the concept being studied, rather than some other factor. This allows researchers to make sound conclusions based on their findings. Different forms of validity include content validity, criterion-related validity, and construct validity, each addressing different aspects of how well a tool measures the intended construct.

In contrast, reliability pertains to the consistency of a measurement tool, indicating how repeatable the results are under similar conditions. Sensitivity and specificity relate to diagnostic tests. Sensitivity measures the ability of a test to correctly identify those with the condition (true positives), while specificity measures the ability to correctly identify those without the condition (true negatives). Therefore, these terms refer to different aspects of measurement and assessment, underscoring why validity is the correct choice for this question.